Apatornis

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Apatornis
Temporal range:
Ma
↓
Holotype of A. celer
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Clade: Avialae
Clade: Ornithurae
Genus: †Apatornis
Marsh, 1873b
Species:
†A. celer
Binomial name
†Apatornis celer
(Marsh, 1873a)
Synonyms

Apatornis is a

ornithuran dinosaurs endemic to North America during the late Cretaceous. It currently contains a single species, Apatornis celer, which lived around the Santonian-Campanian boundary, dated to about 83.5 million years ago. The remains of this species were found in the Smoky Hill Chalk of the Niobrara Formation in Kansas, United States
. It is known from a single fossil specimen: a synsacrum, the fused series of vertebrae over the hips.

While the known fossil remains are very incomplete, enough has been found to reasonably estimate that the body length was between 7–8 inches (18–20 cm).[1]

The type specimen of A. celer, YPM 1451, was reportedly discovered by

Iaceornis marshi.[3]

Classification

The traditional genus Apatornis has been defined as a clade, specifically as all species more closely related to the type specimen YPM 1451 than to either Ichthyornis or modern birds.[3]

Apatornis celer was recognized as a distinct species by Marsh (1873). Its type species was originally classified as Ichthyornis celer. A. celer was long allied with

modern birds, a hypothesis also supported by Hope in 2002.[3] In 2022, Benito and colleagues noted the variability in the sacral anatomy among known Ichthyornis specimens, and suggested that the validity of Apatornis should be re-evaluated.[4]

Its exact relationships are unresolved, mainly due to the paucity of fossil remains. Though it has sometimes been considered to be closely related to modern waterfowl (Anseriformes),[5] most researchers today consider it to be an early member of the clade Ornithurae.[3]

References

  1. ISBN 0895770652
    .
  2. ^ O. C. Marsh. 1873. On a new sub-class of fossil birds (Odontornithes). American Journal of Science and Arts 5(2):161-162
  3. ^ a b c d Clarke, J.A. (2004). "Morphology, phylogenetic taxonomy, and systematics of Ichthyornis and Apatornis (Avialae: Ornithurae)." Bulletin of the American Museum of Natural History, 1-179.
  4. PMID 36545383
    .
  5. ^ Chiappe, L.M., & Dyke, G.J. (2002). "The Mesozoic radiation of birds." Annual Review of Ecology and Systematics, 91-124.
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